Exposing a port on a live Docker container

Readme.md

docker exec -it <containterid> ssh -R5432:localhost:5432 <user>@<hostip>

By default, OpenSSH only allows connecting to remote forwarded ports from the server host. However, the GatewayPorts option in the server configuration file sshd_config can be used to control this. The following alternatives are possible:

GatewayPorts no

This prevents connecting to forwarded ports from outside the server computer.

GatewayPorts yes

This allows anyone to connect to the forwarded ports. If the server is on the public Internet, anyone on the Internet can connect to the port.

GatewayPorts clientspecified

This means that the client can specify an IP address from which connections to the port are allowed. The syntax for this is:

ssh -R 52.194.1.73:8080:localhost:80 host147.aws.example.com

In this example, only connections from the IP address 52.194.1.73 to port 8080 are allowed.

Dockerfile

FROM debian:7

RUN apt-get update && \
    apt-get -y install socat && \
    apt-get clean

USER nobody

CMD socat -dddd TCP-LISTEN:1521,reuseaddr,fork TCP:db:1521

expose_port_on_live_docker_container.txt

# docker run \
  --rm \
  -p $PORT:1234 \
  verb/socat \
    TCP-LISTEN:1234,fork \
    TCP-CONNECT:$TARGET_CONTAINER_IP:$TARGET_CONTAINER_PORT